The invention relates to feeding mechanisms for printing presses and more particularly to feeding mechanisms that are suited for feeding envelopes into a high speed printing press.
There is a body of art relating to mechanisms for feeding paper and envelopes to a printing press. Envelopes present a unique problem that relates to the physical configuration of an envelope in that it is composed of two layers of paper and has a hinged flap on one side.
The following references are representative of prior art:
U.S. Pat. No. 3,175,822 Feeding Mechanism for Envelopes H. A. Benson Mar. 30, 1965. Feeding mechanism with conveyor belt, arcuate path to feeding cylinder (withdrawal cylinder), feed control arms. No Vacuum. No multiple feeding capability.
U.S. Pat. No. 3,160,293 Device For Stacking Letters etc. M. Hennequine, Dec. 8, 1964. Conveyor belt and table for stacking letters etc. in convenient stacks.
U.S. Pat. No. 2,988,355 Single Letter Feeding Device J. Rabinow June 13, 1961. Swinging tubular arms with vacuum pick-up and stacking.
U.S. Pat. No. 2,554,578 Envelope Feeding Machine J. R. Lauffer May 29, 1951. Picks up envelopes from conveyor belt by means of rotating cylinder. Has fingers for opening the flaps of the envelopes before printing. A jet of compressed air assists in blowing open the flaps - Adjustable for different envelope sizes.
U.S. Pat. No. 2,554,577 Envelope Feeder J. R. Lauffer May 29, 1951. Picks envelopes from a stack on a table. Uses sprocket wheels and chains to transport envelopes. Fingers on the chain grasp the envelopes by the flap.
U.S. Pat. No. 2,138,343 Feeding Mechanism For Offset Printing Machines. P. H. Durup Nov. 29, 1938. Vertically stacked envelopes. Bottom envelope is pulled out by arms with suction cups and placed on belt carrier.
U.S. Pat. No. 1,854,221 Feeding Mechanism. C. L. Post April 19, 1932. Stacked envelopes in a magazine. Unique finger pulls out flap from bottom envelope. Chains on sprocket wheels moves envelope to printing rollers.
The present invention teaches the construction of a novel envelope feeding mechanism ("Feeder") that is configured as an attachment to a conventional printing press ("Press") press and may in a preferred embodiment be coupled to the press in such a way that it obtains mechanical power and air vacuum from the press. The feeder is uniquely suitable for taking envelopes to be imprinted from one, two or several parallel operating appended feeder trays that feed the press envelopes from each tray simultaneously with each printing cycle. The feeder employs a unique rotating feeder drum ("flywheel") coordinated with a parallel feed roller and a vacuum pick-up arrangement that "grabs" each envelope and places it on conveyor belts that bring the envelopes to the entrance of the printing press. The feeder mechanism, as will be explained in greater detail in the following disclosure, has a unique capability of taking envelopes of almost any shape and size and even envelopes that have been crumbled or mutilated may be handled by the feeder at a very high speed. The feeder is capable of operating unattended for long periods of time due to the fact that the feeding trays are open ended and may be very long so that they may contain large quantities of unprinted envelopes. The feeder, as described, has electronic controls that monitor the feeding process and stops the printing process in case of malfunctions so that the envelope stock is not destroyed or wrongly imprinted or so that unused ink is not smeared over the surfaces of the printing apparatus.